The metabolism of chondroitin SO4 in cultured chick embryo chondrocytes will be studied. Work will focus on the effect of culture conditions on the activity of the cells in synthesis of chondroitin-6-SO4 and chondroitin-4-SO4 from labeled precursors and on the metabolic steps involved in the secretion of these polymers from the cell and in their catabolism. Studies will be carried out with chondrocytes taken from histologically distinct regions of the tibiotarsus and with limb bud mesenchyme cells which develop the chondrocyte phenotype in monolayer cultures. In addition studies will be performed on the proteins and glycoproteins secreted by these cells to determine whether the stage of differentiation of these cells determines the nature of these secreted products. BIBLIOGRAPHIC REFERENCES: Jung Ja Kim and H. Edward Conrad, Kinetics of Mucopolysaccharide and Glycoprotein Synthesis by Chick Embryo Chondrocytes. Effect of D-Glucose Concentration in the Culture Medium, J. Biol. Chem. 251 6217 (1976).